My personal feeling is that flying's more about attitude and knowledge, the skill bit comes with time, and I can't think of anything about your disability that'd hamper your long term ability.
I wouldn't have thought your missing a lower leg below the knee would cause much of a problem with the brake or rudder pedal. A lack of articulation of the right wrist/elbow could need more work, I guess your instructor/examiner will be very interested in how you manage emergency procedures.
(And let's face it, it's more about attitude and knowledge than anything else.)
Keep us posted.
And never trust a black dog, eventually they
will eat through your kitchen
